Fractionation and identification of pig lymph node plasma membrane glycoproteins

Plasma membrane vesicles purified from pig mesenteric lymph node tissue were solubilized in 1% (w/v) sodium deoxycholate and the fractionation of both membrane proteins and glycoproteins assessed by gel filtration on AcA 34. Milligram quantities of the glycoprotein fraction, consisting of 12 distinct bands on SDS-PAGE ranging in apparent mol. wt from 12,000 to 250,000, were purified by affinity chromatography on lentil lectin-Sepharose. Identified among these by specific immunoprecipitation were the major histocompatibility antigen, SLA (band 9), in association with beta 2-microglobulin (band 12); as well as the alpha (band 10) and beta (band 11) subunits of the Ia-like antigens. A tentative identification of the membrane-bound immunoglobulins (IgM, IgG and IgA) was also proposed on the basis of their known affinities for protein A. Thus, the domestic pig represents and inexpensive, abundant source of defined lymphocyte plasma membrane glycoproteins suitable for further structural analysis.